function Map() {
    this.elements = new Array();
// 获取Map元素个数
    this.size = function() {
        return this.elements.length;
    },
// 判断Map是否为空
        this.isEmpty = function() {
            return (this.elements.length < 1);
        },
// 删除Map所有元素
        this.clear = function() {
            this.elements = new Array();
        },
// 向Map中增加元素（key, value)
        this.put = function(_key, _value) {
            if (this.containsKey(_key) == true) {
                if (this.containsValue(_value)) {
                    if (this.remove(_key) == true) {
                        this.elements.push({
                            key : _key,
                            value : _value
                        });
                    }
                } else {
                    this.elements.push({
                        key : _key,
                        value : _value
                    });
                }
            } else {
                this.elements.push({
                    key : _key,
                    value : _value
                });
            }
        },
        this.set = function(_key, _value) {
            if (this.containsKey(_key) == true) {
                if (this.containsValue(_value)) {
                    if (this.remove(_key) == true) {
                        this.elements.push({
                            key : _key,
                            value : _value
                        });
                    }
                } else {
                    this.elements.push({
                        key : _key,
                        value : _value
                    });
                }
            } else {
                this.elements.push({
                    key : _key,
                    value : _value
                });
            }
        },
        // 获取指定key的元素值value，失败返回null
        this.get = function(_key) {
            try {
                for (i = 0; i < this.elements.length; i++) {
                    if (this.elements[i].key == _key) {
                        return this.elements[i].value;
                    }
                }
            } catch (e) {
                return null;
            }
        },
// 删除指定key的元素，成功返回true，失败返回false
        this.remove = function(_key) {
            var bln = false;
            try {
                for (i = 0; i < this.elements.length; i++) {
                    if (this.elements[i].key == _key) {
                        this.elements.splice(i, 1);
                        return true;
                    }
                }
            } catch (e) {
                bln = false;
            }
            return bln;
        },
// set指定key的元素值value
        this.setValue = function(_key, _value) {
            var bln = false;
            try {
                for (i = 0; i < this.elements.length; i++) {
                    if (this.elements[i].key == _key) {
                        this.elements[i].value = _value;
                        return true;
                    }
                }
            } catch (e) {
                bln = false;
            }
            return bln;
        },
// 获取指定索引的元素（使用element.key，element.value获取key和value），失败返回null
        this.element = function(_index) {
            if (_index < 0 || _index >= this.elements.length) {
                return null;
            }
            return this.elements[_index];
        },
// 判断Map中是否含有指定key的元素
        this.containsKey = function(_key) {
            var bln = false;
            try {
                for (i = 0; i < this.elements.length; i++) {
                    if (this.elements[i].key == _key) {
                        bln = true;
                    }
                }
            } catch (e) {
                bln = false;
            }
            return bln;
        },
// 判断Map中是否含有指定key的元素
        this.has = function(_key) {
            var bln = false;
            try {
                for (i = 0; i < this.elements.length; i++) {
                    if (this.elements[i].key == _key) {
                        bln = true;
                    }
                }
            } catch (e) {
                bln = false;
            }
            return bln;
        },
// 判断Map中是否含有指定value的元素
        this.containsValue = function(_value) {
            var bln = false;
            try {
                for (i = 0; i < this.elements.length; i++) {
                    if (this.elements[i].value == _value) {
                        bln = true;
                    }
                }
            } catch (e) {
                bln = false;
            }
            return bln;
        },
// 获取Map中所有key的数组（array）
        this.keys = function() {
            var arr = new Array();
            for (i = 0; i < this.elements.length; i++) {
                arr.push(this.elements[i].key);
            }
            return arr;
        },
// 获取Map中所有value的数组（array）
        this.values = function() {
            var arr = new Array();
            for (i = 0; i < this.elements.length; i++) {
                arr.push(this.elements[i].value);
            }
            return arr;
        };
    /**
     * map遍历数组
     * @param callback [function] 回调函数；
     * @param context [object] 上下文；
     */
    this.forEach = function forEach(callback,context){
        context = context || window;
//IE6-8下自己编写回调函数执行的逻辑
        var newAry = new Array();
        for(var i = 0; i < this.elements.length;i++) {
            if(typeof callback === 'function') {
                var val = callback.call(context,this.elements[i].value,this.elements[i].key,this.elements);
                newAry.push(this.elements[i].value);
            }
        }
        return newAry;
    }
}